Since the development and application of rotary screen printing presses in the 1960's, belt driven conveyor ovens have been used to fully cure screen printed inks onto textiles. Current screen printing ovens heat a flat-laying printed textile with the image facing up on a moving belt, normally arranged in a flattened or horizontal configuration, with a heat source being arranged thereabove, and utilizing either radiation and/or convention means for curing of the applied inks. Oven chambers can vary in many ways, and in sizes, but the horizontal orientation of the heat source and the substrate to which the heat is applied has generally remained the same.
Two main types of energy powering current ovens is one formed operating from electricity, and the other is from gas combustion. Energy efficiency is an important feature for the oven owners. Particularly where gas combustion is used, energy loss can be significant. And, controlling energy loss is a constant battle for the oven manufacturers, and particularly their customers, especially regarding paying the utility bills to operate and run these systems. Energy loss can be extensive and difficult to measure, but should be defined as the total energy consumed less the energy transferred to the printed textile. In the case of today's electrically powered radiant heaters positioned above the textile, such as clothing products, or any other substrates to which printing inks are applied, energy losses stem from direct radiation upon the oven chamber surfaces other than the belt and printed textile per se. Energy loss can also be significantly encountered where the heat escapes from the oven enclosure, such as at its entrance or exits, during usage. Losses also occur through conduction of the heat through the materials in contact with the heating elements, such as brackets and even insulation on the backside of the elements. In the case of today's gas fired ovens, energy losses come primarily from energy wasted heating of the plenum(s) leading to the diffuser(s) above the printed textile. In both cases, there are oven chamber surfaces heated that do not contribute to the curing of the printed textile, and they are the primary sources for measurable energy loss. This is an expensive energy loss to the business owner.
Printers use a wide variety of inks requiring different curing temperatures and schedules. Inks and coatings manufacturers generally only show one curing schedule. Printers, however, must consider cure-time schedules under different time-temperature conditions to optimize space, equipment, and process, minimize cost, and assure that the finished products meet the specifications set in place for quality control and by the end user. It is understood in the industry that more consistent ink cross linking, textile adhesion, and wash fastness comes from controlled heat transfer with longer dwell times. Dwell time is defined as the time the product is in the oven chamber. It must be sufficient to bring the thickness of the ink layer through its cure temperature, without over-heating the ink or substrate.
It is also important to note that a longer oven chamber can lengthen the dwell time and/or increase the production rate. A disadvantage of today's oven designs and their horizontal orientation is the additional equipment cost, energy loss, and energy consumption associated with buying a longer oven chamber. To compensate, some newer oven designs have shorter oven chambers and higher wattage radiant heating elements or higher BTU gas burners. This is not a better solution. Production rates are inflated, more energy is consumed, and curing quality is sacrificed.
Examples of various structures and functioning for curing ovens, even for clothing products, such as shirts, can be seen in the following prior art patents. For example, U.S. Pat. No. 4,028,051 shows a Curing Oven for Mineral Wool.
U.S. Pat. No. 4,603,491, to Hengle, et al, shows a Reversible Cross Flow Drying or Curing Oven.
The patent to Salisbury, et al, U.S. Pat. No. 4,694,180, shows a Curing Oven for Adhesive.
The patent to Kersting, U.S. Pat. No. 4,717,339, shows what appears to be a rack style of Curing Oven.
The patent to Cornell, U.S. Pat. No. 4,825,561, shows a Curing Oven Apparatus, apparently for curing items in a flat or horizontal arrangement.
The patent to Braun, U.S. Pat. No. 5,018,966, shows a Strip Drying or Curing Oven. This particular device apparently shows in inline style of curing oven, where the items enter one end, and exit the other.
The patent to Chang, et al, U.S. Pat. No. 5,033,203, shows a Curing Oven Using Wellsbach Conversion.
The design patent to Neal, Des. 360,423, shows a Screenprint Curing Oven, apparently for drying printed items passing through the heater on a horizontal belt.
The patent to Bishop, et al, U.S. Pat. No. 6,267,587, shows a Thermal Curing Oven and Thermal Curing Process.
The patent to Smith, U.S. Pat. No. 6,394,796, shows a Curing Oven Combining Methods of Heating.
The patent to Rogers, Jr., et al, U.S. Pat. No. 8,038,436, shows another Textile Curing Oven with Active Cooling.
A variety of published applications show various types of textile curing ovens, for bonding adhesives to the back surface of textile articles, as can be seen in the Published Application No. US 2008/0193890, in addition to Published Application No. US 2010/0119985. These are examples of available prior art style of curing ovens, some of them for curing the adhesive, or print, upon textiles.